The present research plan examines the neuroanatomical basis for complex learning in the budgerigar. Much is already known about basic neuroethological processes in this species from studies of vocalizations, hearing, and the ethology and physiology of reproductive behavior and the neuroanatomy of the CNS. For this reason the budgerigar offers a unique model for examining the interaction of basic biological factors in learning. Three related sets of experiments are proposed. First, neuroanatomical and pathway tracing techniques will be used to extend a study of the pathways involved in the processing of acoustic information in the central nervous system of the budgerigar - work that was initiated and is currently funded with a small grant from NIMH. Second, an operant conditioning procedure already proven successful in this species will be modified to allow the application of sophisticated multidimensinal scaling tecniques to examine, for the first time, perceptual learning of natural acoustic and visual stimuli. Third, guided by the knowledge gained from the above pathway tracing, operant conditioning, and multidimensional scaling experiments, these techniques will be combined to examine the effect of lesioning selected brain areas and pathways on learning. This blend of techniques provides a unique opportunity to explore the neural basis of the integration or intermodal association of auditory and visual information during learning. By addressing general biological issues, the present research plan will offer some penetrating insights into the basic biological foundations of learning common to all complex vertebrates including humans.